The theme for the night on the ballroom bash was "Most Memorable Year," and that led to the surprising admission from the star.

"Most people would think my most memorable year would be the year 'Malcolm in the Middle' started (2000), because it allowed me to live all of these dreams of mine," he said. "It almost feels like it wasn't me. There's no negative feelings. I just don't necessarily remember."

Frankie Muniz on "Malcolm in the Middle" (2000). (C)20thCentFox/Courtesy Everett

While the 31-year-old doesn't know how or exactly when the problem began, he explained that he's "had nine concussions" and suffered "a fair amount of mini strokes" over the years.

"I'm not saying those things correlate exactly to why my memory's not great, but I guess if you think about it, it could be," he said.

Now, with help, he's able to retrieve some memories. His girlfriend writes a daily journal of their activities together so he can always get a refresher.

As for the older memories, someone else helps with that.

"I told him not to worry about what you remember or what you don't remember," his former TV father, Bryan Cranston, said. "They are still (his) experiences. It'll be my job. I will tell him, 'Remember this, remember that on 'Malcolm?' What a life!"